The earliest forms of wiring homes (1920s-1950s) utilized wire insulated with shellac permeated cloth wrap. Asphalted cloth wrap was used for insulation in the 1950s-1970s. Aluminum electrical wiring was installed in homes in the mid 1960s through the mid 1970s. Wire, as we know it today with two insulated inner conductors (e.g., hot/neutral or electrifiable/return conductors) and a non-insulated ground conductor (e.g., grounding conductor), all within a thermoplastic outer insulator, has been used since the mid-1950s.
FIGS. 1A-B illustrate examples of such conventional electrical wire. As illustrated in FIG. 1A, one conventional electrical wire 50 includes an electrifiable (e.g., hot) conductor 55 surrounded by a first insulation layer 60, a return (e.g., neutral) conductor 65 surrounded by a second insulation layer 70. A third insulation layer 75 surrounds the insulated conductors 55, 65.
As illustrated in FIG. 1B, another conventional electrical wire 100 includes an electrifiable (e.g., hot) conductor 105 surrounded by a first insulation layer 110, a return conductor 115 surrounded by a second insulation layer 120, and a grounding conductor 125. A third insulation layer 130 surrounds all of the conductors 105, 115 and 125.
Many millions of homes today are facing end-of-life scenarios regarding their older wiring and run significant risk of fire damage and casualties. According to the National Science and Technology Council November 2000 report, “[w]ire systems may become unreliable or fail altogether, due to poor design, use of defective materials, improper installation, or other causes. The risk of failure increases as wire systems age, due to cumulative effects of environmental stresses (e.g. heat, cold, moisture, or vibration), inadvertent damage during maintenance, and the wear and tear of constant use. The aging of a wire system can result in loss of critical function in equipment powered by the system . . . can jeopardize public health and safety and lead to catastrophic equipment failure or to smoke and fire.” The Consumer Products Safety Commission estimates that 50 million homes in the United States have reached or are about to reach the “end-of-life” of their electrical wiring system.
Furthermore, wire insulation and/or conductors can deteriorate due to radiation, high temperature, steam, chafing, mishandling, corrosion, mechanical loading, and vibration. Reports issued by the Consumer Products Safety Commission (CPSC) show that in 1997 home wire systems caused over 40,000 tires that resulted in 250 deaths and over $670 million of property damage. Further study by the CPSC based on 40,300 electrical circuit fires showed that 36% were due to installed wiring and 16% were due to cord/plugs. Along with the usual wire system failures due to age and environmental stresses, aluminum wire systems were “prone to degradation and dangerous overheating”.
Regarding modern wire systems and technology, the National Institute of Standards and Technology (NIST) and Building and Fire Research Laboratory (BFRL) acknowledge, “[w]ires and cables made with fluorocarbons have excellent flammability, but are very expensive. Flame-retarded polyvinyl chloride (PVC) cables also have excellent flammability and physical properties . . . . However, the chloride content of (all) PVC cables is a concern for potential formation of dioxin during incineration.”
As illustrated in FIGS. 1A-B, conventional electrical wire which is commonly used in homes and offices today consist of solid, round wires individually insulated with PVC (except for the ground wire) with an outer PVC jacket surrounding the inner wires. Fires are increasingly being caused by overheated wires, insulation breakdown, and penetrations. The open spaces afforded by conventional in-wall or in-ceiling wiring offer plenty of oxygen for fire ignition and expansion associated with electrical fires.
Moreover, such conventional electrical wire poses an electric shock hazard and therefore, causes safety concerns. That is, such conventional electrical wire is often accidentally penetrated by objects such as nails, screws, drill bits, etc. which often results in the serious injury or death. Thus, such conventional electrical wire has a high potential for serious injury when penetrated by any of the aforementioned electrically conductive objects.
Other key examples of conventional wiring systems being inadequate in the changing-marketplace include:
(a) the proliferation of solid wall (and ceiling) construction techniques; and
(b) the proliferation of new technologies and devices being installed in new and especially existing home and office environments that require wire interfaces and many are designed for surface mounting of these devices.
New materials such as foam block forms for poured concrete walls, removable form poured concrete walls, fabricated alternative materials to wood and recycled materials formed into solid wall (and ceiling) panels all represent better long-term characteristics and advantages over current “hollow” exterior and interior wall (and ceiling) construction techniques. These solid material construction techniques require some type of invasive channeling done on-site. This channeling has many drawbacks, safety concerns and costs associated. It also typically places the wiring closer to the finished surface where future invasions as previously described may cause shock or potential arch faults and fire potential. On a global scale the construction issues have existed for many years based on differences in construction techniques.
In addition, the advent of advances in audio, video and computer/internet applications have drastically changed the paradigm of home and Office devices. Surround-sound home theater and multi-media conference room audio systems, flat-panel plasma and liquid crystal display (LCD) televisions, networked homes and offices, new applications of lighting, air quality and control systems have put tremendous strains and in many cases compromises on wiring systems. The requirement for alternating current (AC) or direct current (DC) electrical power interfaces and the associated wiring has created problems for the installer and the user.